Twist-angle dependent proximity induced spin-orbit coupling in graphene/topological insulator heterostructures

The authors investigate the proximity-induced spin-orbit coupling in twisted graphene/topological insulator (Bi₂Se₃ and Bi₂Te₃) heterostructures from first principles. Fitting the band structures around the graphene Dirac cone to an established spin-orbit Hamiltonian yields the twist angle dependencies of the spin-orbit couplings. Amongst other findings, an interesting form of the Rashba spin-orbit coupling arises for such structures. It entails a large radial component of the in-plane spin structure around the Dirac cone, which can be used to realize collinear charge-to-spin conversion.